Straight line telescopic drive

Abstract

The present disclosure provides a linear telescopic driving device, comprising a fixed seat, a driving mechanism, a driving shaft assembly and a guide rod assembly. The driving mechanism is arranged on the fixed seat. The driving shaft assembly is composed of multiple levels of driving shafts nested with each other. The first level of driving shaft is rotatably arranged on the fixed seat. The subsequent driving shafts are nested in the previous level and the outer surface is provided with a spiral raceway. Except for the last level, the remaining driving shafts are provided with a rolling ball inside and rolling fit with the spiral raceway of the next level. The guide rod assembly is composed of multiple levels of guide rods nested with each other. The first level of guide rod is fixed on the fixed seat. The last level of guide rod is fixed on the last level of driving shaft. The adjacent guide rods can only axially slide and are constrained from rotating circumferentially. When the driving mechanism drives the first level of driving shaft to rotate, the rolling ball rolls along the spiral raceway, which converts the rotary motion of the driving shaft into the linear motion of the next level of driving shaft step by step, and finally drives the last level of driving shaft to make telescopic linear motion.

Description

Technical Field

[0001] This disclosure relates to a linear telescopic drive device, belonging to the field of mechanical automation. Background Technology

[0002] Linear drive devices are key actuators in automated equipment, robots, and systems requiring precision operations within confined spaces. Their performance directly impacts the equipment's accuracy, stability, and space utilization. Currently, the mainstream technologies for achieving linear telescopic motion include trapezoidal lead screws, rack and pinion gears, and synchronous belt drives.

[0003] Chinese patent CN107127749A discloses a linear drive device based on a motor-driven screw. While this solution can achieve linear motion, its main drawbacks are: First, to achieve the telescopic function, its structure is typically bulky, resulting in a large overall size and weight, which is unsuitable for applications with limited space or weight sensitivity. Second, the screw and related parts require high machining precision, leading to complex manufacturing processes and high costs. Finally, the structural design makes it difficult to efficiently achieve multi-stage telescopic movement, significantly limiting the range of motion.

[0004] Chinese patent CN119283010A proposes a mechanism for multi-stage drive using an arc-shaped stainless steel belt in conjunction with a synchronous belt. This solution attempts to address the multi-stage drive problem, but its main drawbacks are: First, the overall structural design is complex, including the arc-shaped belt, synchronous belt, and associated tensioning and guiding mechanisms, resulting in a relatively large size and high cost. Second, the core transmission element—the arc-shaped stainless steel belt—continuously deforms during movement, affecting the smoothness of the transmission.

[0005] Therefore, existing linear drive devices, especially those used in multi-stage telescopic scenarios, generally suffer from prominent problems such as complex structure, large size and weight, high manufacturing cost, insufficient transmission stability, and difficulty in balancing compactness and large stroke. They are unable to meet the growing demand of modern industrial equipment for miniaturized, lightweight, highly reliable, and low-cost linear drive devices.

[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Utility Model Content

[0007] This disclosure provides a linear telescopic drive device.

[0008] According to one aspect of this disclosure, a linear telescopic drive device is provided, comprising: Fixed base; A drive shaft assembly includes at least two drive shafts. One end of the first-stage drive shaft is rotatably mounted on the fixed base. The remaining drive shafts are nested inside the previous-stage drive shaft and are provided with helical raceways. The helical raceways are channels that extend helically along the outer surface of the drive shaft. The first-stage to penultimate-stage drive shafts are provided with balls, which cooperate with the helical raceways of the next-stage drive shaft through the balls. The guide rod assembly includes a number of guide rods equal to the number of drive shafts. One end of the first-stage guide rod is fixedly mounted on the fixed base. The remaining guide rods are nested inside the previous-stage guide rod. Adjacent stages of the guide rods can only move relative to each other along their length and are constrained to rotate circumferentially by their cross-sectional shapes. The last-stage guide rod is fixedly mounted on the last-stage drive shaft. A drive mechanism is mounted on the fixed base and is connected to the first-stage drive shaft for transmission. When the drive mechanism drives the first-stage drive shaft to rotate, the balls in the upper-stage drive shaft roll and cooperate with the helical raceway of the lower-stage drive shaft, converting the rotational motion of the upper-stage drive shaft into the linear motion of the lower-stage drive shaft, and finally driving the last-stage drive shaft to move linearly along the length direction.

[0009] According to one aspect of the technical solution disclosed herein, when the drive mechanism drives the first-stage drive shaft to rotate, the balls inside the upper-stage drive shaft roll within the helical raceway of the lower-stage drive shaft. Due to the special shape of the helical raceway, this rolling engagement converts the rotational motion of the upper-stage drive shaft into the linear motion of the lower-stage drive shaft, and this motion is transmitted sequentially through multiple drive shafts, ultimately driving the last-stage drive shaft to move linearly along its length. Simultaneously, adjacent guide rods can only move relative to each other along their length, and their cross-sectional shapes constrain their circumferential rotation. This design ensures that the drive shaft does not rotate circumferentially during linear motion, thereby guaranteeing the stability of the linear motion and enabling the last-stage drive shaft to move along a predetermined linear trajectory.

[0010] This disclosure solves the problem of complex structures. Compared with screw drive schemes and synchronous belt drive schemes, this device achieves multi-stage telescopic function through the cooperation of the internal balls and helical raceways of the drive shaft assembly and the nested guiding design of the guide rod assembly. It does not require the screw length to meet the requirements of the drive stroke, nor does it require the setting of complex structures such as arc belts, synchronous belts and matching tensioning and guiding mechanisms, resulting in a simpler and more compact structure.

[0011] This disclosure solves the problems of large size and weight. The drive shaft assembly and guide rod assembly of this device adopt a nested design with a hollow structure, making full use of space. While achieving multi-stage telescopic movement, it effectively reduces the overall size, realizes the lightweight of the device, and is more suitable for use in applications with limited space or high weight requirements.

[0012] This disclosure solves the problem of high manufacturing costs. Compared with the high precision requirements and complex manufacturing processes of the lead screw and related parts in the screw drive scheme, the structure of this device is relatively simple, with fewer parts, reducing the requirements for machining precision and thus lowering manufacturing costs. At the same time, this device avoids the use of complex core transmission components such as the curved stainless steel belt in the gear and rack scheme, reducing the application of high-cost parts and further reducing manufacturing costs.

[0013] This disclosure solves the problem of insufficient transmission stability. The guide rod assembly constrains the circumferential rotation of the drive shaft, ensuring the accuracy of linear motion and avoiding the disadvantage of continuous deformation of the synchronous belt in synchronous belt drive schemes, which affects transmission stability.

[0014] According to at least one embodiment of the linear telescopic drive device of the present disclosure, the drive shafts from the first stage to the penultimate stage are fixedly provided with bushings, and the balls are disposed on the inner surface of the bushings.

[0015] In this embodiment, when the drive shaft rotates, the bushing rotates accordingly, causing the balls to roll within the helical raceway, thus achieving motion conversion. This arrangement allows the bushing to better protect the balls, reduce wear, improve the stability and reliability of the ball-helical raceway engagement, and extend the device's service life. Furthermore, placing the balls on the bushing instead of directly on the end of the drive shaft reduces the machining difficulty and cost of the drive shaft.

[0016] According to at least one embodiment of the linear telescopic drive device of the present disclosure, a bushing is fixedly provided at the end of the last stage drive shaft, and the end of the last stage guide rod is fixedly connected to the bushing.

[0017] In this embodiment, when the last-stage drive shaft moves linearly, it drives the last-stage guide rod to move synchronously via the bushing. The bushing connects the last-stage drive shaft and the guide rod, making the connection between them more stable.

[0018] According to at least one embodiment of the linear telescopic drive device of the present disclosure, the drive mechanism is a hollow motor, the hollow motor has a channel inside, and a first-stage guide rod is fixedly disposed in the channel.

[0019] In this embodiment, a hollow motor drives the first-stage drive shaft to rotate, while the first-stage guide rod is fixed within the hollow motor channel, providing stable support for the entire device. Using a hollow motor as the drive mechanism results in a compact structure, saves space, and the hollow motor channel can be used to fix the guide rod, making the device layout more rational, reducing additional fixing structures, lowering costs, and improving the device's integration.

[0020] According to at least one embodiment of the linear telescopic drive device of the present disclosure, the guide rod is provided with a through hole extending along the length direction, and the rods are nested sequentially through the through hole; the last stage bushing is provided with a clearance hole that is opposite to and communicates with the through hole; the linear telescopic drive device further includes a drag chain, which is disposed in the through hole of the guide rod, with one end extending from the clearance hole to the outside and the other end extending from the channel of the hollow motor to the outside.

[0021] In this embodiment, the cable chain can be used to house and protect components such as cables within the device, preventing damage as the device moves. Furthermore, the cable chain is positioned inside a guide rod, which in turn is located inside the drive shaft. This improves the appearance, makes the structure more compact, and reduces the overall structural size.

[0022] According to at least one embodiment of the linear telescopic drive device of the present disclosure, a limiting device is provided between two adjacent drive shafts and between two adjacent guide rods. The limiting device is used to limit the relative range of movement of the two adjacent drive shafts or the two adjacent guide rods in the length direction so as to keep them in a nested state.

[0023] In the technical solution of this embodiment, when the drive shaft or guide rod moves relative to each other in the length direction, the limiting device restricts the relative movement range to prevent disengagement due to excessive movement.

[0024] According to at least one embodiment of the linear telescopic drive device of the present disclosure, an elastic element is provided between the ball and the bushing on which the ball is mounted, and the elastic element is supported by the bushing to push the ball to contact the inner wall of the corresponding helical raceway.

[0025] In this embodiment, when the drive shaft rotates, the elastic element ensures that the balls are always in close contact with the helical raceway, achieving stable rolling fit. The elastic element can automatically compensate for the gap between the balls and the helical raceway, ensuring that the balls and the helical raceway are always in good contact, reducing impact and vibration during movement, improving the smoothness and accuracy of motion transition, and reducing noise.

[0026] According to at least one embodiment of the linear telescopic drive device of the present disclosure, the balls are arranged in groups on the same bushing, and each group of balls includes at least two balls spaced apart; the helical raceways are arranged in groups on the same drive shaft, and each group of helical raceways includes at least two helical raceways spaced apart, and the helical raceways are arranged one-to-one with the balls.

[0027] In the technical solution of this embodiment, when the drive shaft rotates, multiple sets of balls and helical raceways cooperate simultaneously to achieve motion conversion. The grouping of balls and helical raceways increases the contact points and force points for motion conversion, improves the load-bearing capacity of the device, makes the motion smoother, and simultaneously disperses the force on individual balls and helical raceways, reducing wear and extending service life.

[0028] According to at least one embodiment of the linear telescopic drive device of the present disclosure, when the upper-level drive shaft drives the corresponding bushing to rotate, and the lower-level drive shaft has rotational freedom in the same rotational direction as the upper-level bushing, the upper-level bushing engages with the helical raceway of the lower-level drive shaft through ball bearings to drive the lower-level bushing to rotate; when the bushing of the upper-level drive shaft rotates, and the bushing of the lower-level drive shaft cannot rotate in the same direction as the upper-level bushing under the constraint of the guide rod or the bushing of the next lower level, the lower-level drive shaft and its bushing move linearly along its length direction.

[0029] According to at least one embodiment of the linear telescopic drive device of the present disclosure, the guide rod is a polygonal tube with a polygonal cross-section.

[0030] In the technical solution of this embodiment, a polygonal tube is used as the guide rod, which has a simple structure. The cross-sectional shape can effectively constrain circumferential rotation, eliminating the need for additional complex structures to achieve the guiding function, reducing manufacturing costs, and ensuring the accuracy and stability of the guidance. Attached Figure Description

[0031] The accompanying drawings illustrate exemplary embodiments of the present disclosure and, together with the description thereof, serve to explain the principles of the present disclosure. These drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification.

[0032] Figure 1 This is a schematic diagram of the retracted state of a linear telescopic drive device according to one embodiment of the present disclosure.

[0033] Figure 2 This is a structural schematic diagram of a linear telescopic drive device in its deployed state according to one embodiment of the present disclosure.

[0034] Figure 3 This is a cross-sectional perspective view of a linear telescopic drive device according to one embodiment of the present disclosure.

[0035] Figure 4 This is a schematic diagram of the structure of a drive shaft according to one embodiment of the present disclosure.

[0036] Figure 5 This is a schematic diagram of a bushing with ball bearings according to one embodiment of the present disclosure.

[0037] Figure 6 This is a schematic diagram of the structure of a guide rod according to one embodiment of the present disclosure.

[0038] The specific labels in the attached figures are as follows: 100 Fixed base 110 bearing 120 Outer Ring Fixing Mount 130 Inner Ring Fixing Mount 200 drive shaft assembly 210 First-stage drive shaft 201 Spiral Raceway 220 ball bearings 230 bushing 240 Fourth-stage drive shaft 250 First limit device 300 Guide Rod Assembly 310 First-stage guide rod 320 Fourth-level guide rod 321 Flange 330 Second Limit Device 340 through hole 350 cable chain 400 drive mechanism 410 Hollow Core Motor 411 Output Shaft Detailed Implementation The present disclosure will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the disclosure. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present disclosure are shown in the accompanying drawings.

[0039] It should be noted that, where there is no conflict, the embodiments and features described in this disclosure can be combined with each other. The technical solutions of this disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] When a component is referred to as being "on" or "above" another component, "connected to," or "joined to" another component, the component may be directly on, directly connected to, or directly joined to the other component, or there may be intermediate components. However, when a component is referred to as being "directly on" another component, "directly connected to," or "directly joined to" another component, there are no intermediate components. Therefore, the term "connection" can refer to a physical connection, an electrical connection, etc., and may or may not have intermediate components.

[0041] For descriptive purposes, this disclosure may use spatial relative terms such as “below,” “under,” “below,” “down,” “above,” “above,” “higher,” and “side (e.g., in a “sidewall”)” to describe the relationship between one component and another component as shown in the accompanying drawings. In addition to the orientations depicted in the drawings, the spatial relative terms are also intended to encompass different orientations of the device during use, operation, and / or manufacture. For example, if the device in the drawings is flipped, a component described as “below” or “under” another component or feature would subsequently be positioned “above” said other component or feature. Thus, the exemplary term “below” can encompass both “above” and “below” orientations. Furthermore, the device may be otherwise positioned (e.g., rotated 90 degrees or in other orientations), thus interpreting the spatial relative descriptive terms used herein accordingly.

[0042] The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, unless the context clearly indicates otherwise, the singular forms “a” and “the” are intended to include the plural forms as well. Furthermore, when the terms “comprising” and / or “including” and variations thereof are used in this specification, it indicates the presence of the stated features, integrals, steps, operations, parts, components, and / or groups thereof, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, parts, components, and / or groups thereof. It should also be noted that, as used herein, the terms “substantially,” “about,” and other similar terms are used as approximate terms rather than as terms of degree, thus explaining the inherent biases in measurements, calculated values, and / or provided values ​​that would be recognized by one of ordinary skill in the art.

[0043] This embodiment of a linear telescopic drive device is mainly used in situations requiring precise linear telescopic motion, such as joint driving of robotic arms and material handling in automated equipment.

[0044] Figure 1 This is a structural schematic diagram of a linear telescopic drive device in its retracted state according to one embodiment of the present disclosure. Figure 2 This is a structural schematic diagram of a linear telescopic drive device in its deployed state according to one embodiment of the present disclosure. Figure 3 This is a cross-sectional perspective view of a linear telescopic drive device according to one embodiment of the present disclosure.

[0045] See Figures 1 to 3 As shown, the linear telescopic drive device of this embodiment includes: a fixed base 100, a drive shaft assembly 200, a guide rod assembly 300, and a drive mechanism 400.

[0046] The mounting base 100 has sufficient rigidity and stability. It is a rectangular plate structure with mounting holes at the four corners, and is securely fixed to the base with bolts.

[0047] Figure 4 This is a schematic diagram of the structure of a drive shaft according to one embodiment of the present disclosure.

[0048] like Figure 3 and Figure 4 As shown, the drive shaft assembly 200 includes at least two stages of drive shafts; this embodiment uses a four-stage drive shaft as an example. One end of the first-stage drive shaft 210 is rotatably mounted on the fixed base 100. The remaining drive shafts are nested inside the previous stage drive shaft and are provided with helical raceways 201. The helical raceways 201 are channels that extend helically along the outer surface of the drive shaft. The first to third-stage drive shafts are provided with balls 220 (the balls 220 are the same balls 220 inside the bushing 230 described below), and the balls 220 cooperate with the helical raceways 201 of the next-stage drive shaft.

[0049] like Figure 3 As shown, in one embodiment where one end of the first-stage drive shaft 210 is rotatably mounted on the fixed base 100: a bearing 110 is mounted on the fixed base 100, the outer ring of the bearing 110 is fixed to the outer ring fixed base 120 of the fixed base 100, the inner ring is fixedly connected to the inner ring fixed base 130, and the inner ring fixed base 130 is fixedly sleeved to the outer side of the first-stage drive shaft 210 of the drive shaft assembly 200.

[0050] Figure 5 This is a schematic diagram of a bushing with ball bearings according to one embodiment of the present disclosure.

[0051] like Figure 3 and Figure 5 As shown, the drive shaft can be fitted with ball bearings 220 in the following way: bushings 230 are fixedly installed at the ends of the first, second, and third stage drive shafts by welding, interference fit, or bolts. The inner surface of the bushing 230 is provided with ball bearing mounting grooves, and the ball bearings 220 are installed in these grooves.

[0052] An elastic element (not shown) is provided between the ball bearing 220 and the bushing 230 on which the ball bearing 220 is mounted. For example, the elastic element is a spring. One end of the spring is fixed to the bushing 230, and the other end pushes the ball bearing 220, ensuring that the ball bearing 220 is always in close contact with the inner wall of the corresponding helical raceway 201. The spring force is appropriate, ensuring good contact between the ball bearing 220 and the helical raceway 201 without increasing motion resistance due to excessive force.

[0053] like Figure 2 and Figure 5As shown, to improve the stability and reliability of the helical fit, the balls 220 are grouped together on the same bushing 230, with each group of balls 220 including at least two spaced balls 220. The helical raceways 201 are grouped together on the same drive shaft, with each group including at least two spaced helical raceways 201. Each helical raceway 201 is paired with a ball 220. This embodiment uses the fit of two balls 220 and two helical raceways 201 as an example. The two balls 220 are positioned opposite each other in two ball mounting slots inside the bushing 230. When the drive shaft rotates, the two groups of balls 220 and helical raceways 201 engage simultaneously to achieve motion conversion. The grouped arrangement of the balls 220 and helical raceways 201 increases the contact points and force points for motion conversion, improves the load-bearing capacity of the device, makes the motion smoother, and disperses the force on individual balls 220 and helical raceways 201, reducing wear and extending service life.

[0054] like Figure 3 As shown, a first limiting device 250 is provided between two adjacent drive shafts. For example, the first limiting device 250 is a limiting ring or a retaining ring. Taking a limiting ring as an example, for each drive shaft, a limiting ring is provided at the nested end of each drive shaft. When the drive shafts move to their relative limit positions, the limiting rings collide with each other, restricting their continued movement.

[0055] See Figure 3 As shown, the guide rod assembly 300 includes guide rods in the same number as the drive shafts. Taking a four-stage guide rod as an example, one end of the first-stage guide rod 310 is fixedly mounted on the fixed base 100, and the remaining guide rods are nested inside the previous stage guide rod. Adjacent guide rods can only move relative to each other along their length and are constrained to rotate circumferentially by their cross-sectional shapes. The fourth-stage guide rod 320 is fixedly mounted on the last stage drive shaft.

[0056] like Figure 3 As shown, the fourth-stage guide rod 320 can be fixedly mounted on the last-stage drive shaft in the following way: a bushing 230 is fixedly installed at the end of the fourth-stage drive shaft 240. A flange 321 is provided at the end of the fourth-stage guide rod 320, and the flange 321 is fixedly connected to the third-stage bushing 230 by bolts, so that the fourth-stage guide rod 320 can move synchronously and linearly with the fourth-stage drive shaft 240.

[0057] like Figure 3 As shown, a second limiting device 330 is also provided between two adjacent guide rods. Taking the retaining ring as an example, a retaining ring is provided inside the nested end of each guide rod. When the guide rod moves to the limit position, the retaining ring contacts the retaining ring or shoulder structure of the next guide rod, which plays a limiting role.

[0058] See Figure 3 As shown, to facilitate wiring and simplify the appearance, the guide rod is provided with a through hole 340 extending along its length, and the rods are nested sequentially through the through hole 340. The final stage bushing 230 is provided with a clearance hole that is opposite to and communicates with the through hole 340. The linear telescopic drive device also includes a cable chain 350, which is disposed within the through hole 340 of the guide rod, with one end extending from the clearance hole to the outside and the other end extending from the channel of the hollow motor 410 to the outside. The cable chain 350 can be used to accommodate and protect cables and other components within the device, preventing damage as the device moves. Furthermore, the cable chain 350 is arranged inside the guide rod, which is located inside the drive shaft, thus improving the appearance, making the structure more compact, and reducing the overall structural size.

[0059] Figure 6 This is a schematic diagram of the structure of a guide rod according to one embodiment of the present disclosure.

[0060] See Figure 6 As shown, for example, the guide rod is made of square tubing, and the dimensional accuracy of its inner hole and outer circle is strictly controlled to ensure the nesting fit accuracy between adjacent guide rods. The square cross-sectional shape can effectively constrain the circumferential rotation between adjacent guide rods, allowing the guide rods to move relative to each other only along their length, thus ensuring the accuracy of guidance.

[0061] See Figure 2 and Figure 3 As shown, the drive mechanism 400 is mounted on the fixed base 100 and is connected to the first-stage drive shaft 210 for transmission.

[0062] For example, the drive mechanism 400 is a hollow motor 410, whose housing is fixed to the mounting base 100 by bolts. The output shaft 411 of the hollow motor 410 is connected to the first-stage drive shaft 210 to achieve power transmission. The first-stage guide rod 310 passes through the internal channel of the hollow motor 410 and can be fixed at both ends of the channel by retaining rings to prevent the guide rod from shaking during movement. The hollow motor 410 drives the first-stage drive shaft 210 to rotate, while the first-stage guide rod 310 is fixed in the channel of the hollow motor 410, providing stable support for the entire device.

[0063] When the drive mechanism 400 drives the first-stage drive shaft 210 to rotate, the ball bearings 220 in the upper-stage drive shaft roll in conjunction with the helical raceway 201 of the lower-stage drive shaft, converting the rotational motion of the upper-stage drive shaft into the linear motion of the lower-stage drive shaft, and finally driving the last-stage drive shaft to move linearly along the length direction.

[0064] For example, when the upper-level drive shaft drives the corresponding bushing 230 to rotate, and the lower-level drive shaft has rotational freedom in the same rotational direction as the upper-level bushing 230, that is, the upper-level bushing 230 engages with the helical raceway 201 of the lower-level drive shaft through the ball bearings 220 to drive the lower-level bushing 230 to rotate. When the bushing 230 of the upper-level drive shaft rotates, and the bushing 230 of the lower-level drive shaft cannot rotate in the same direction as the upper-level bushing 230 due to the constraint of the guide rod or the bushing 230 of the next lower level, the lower-level drive shaft and its bushing 230 move linearly along its length. For example, the fourth-level drive shaft 240 does not have rotational freedom due to the restriction of the guide rod. When the third-level drive shaft rotates, it can drive the fourth-level drive shaft 240 to move along its length. When the fourth-level drive shaft 240 moves relative to the third-level drive shaft to the end of its stroke, the third-level drive shaft cannot continue to rotate due to the engagement mechanism of the ball bearings 220 and the helical raceway 201. At this point, the rotation of the second-stage drive shaft and its bushing 230 can drive the linear movement of the third-stage drive shaft. Similarly, the first-stage drive shaft 210 can also drive the second-stage drive shaft to move linearly until the drive shaft assembly 200 is fully deployed.

[0065] In summary, the working principle of the linear telescopic drive device in this embodiment is as follows: When the drive mechanism 400 drives the first-stage drive shaft 210 to rotate, the balls 220 in the upper-stage drive shaft will roll within the helical raceway 201 of the lower-stage drive shaft. Due to the special shape of the helical raceway 201, this rolling engagement converts the rotational motion of the upper-stage drive shaft into the linear motion of the lower-stage drive shaft, and this motion is transmitted sequentially through multiple drive shafts, ultimately driving the last-stage drive shaft to move linearly along its length. Simultaneously, adjacent guide rods can only move relative to each other along their length, and their circumferential rotation is constrained by their cross-sectional shape. This design ensures that the drive shaft does not rotate circumferentially during linear motion, thereby guaranteeing the stability of the linear motion and enabling the last-stage drive shaft to move along a predetermined linear trajectory.

[0066] This embodiment solves the problem of complex structure. Compared with screw drive schemes and synchronous belt drive schemes, this device achieves multi-stage telescopic function through the cooperation of the internal ball bearings 220 and the helical raceway 201 of the drive shaft assembly 200 and the nested guiding design of the guide rod assembly 300. It does not require the screw length to meet the drive stroke requirements, nor does it require complex structures such as arc belts, synchronous belts and matching tensioning and guiding mechanisms, resulting in a simpler and more compact structure. This disclosure solves the problem of large size and weight. The drive shaft assembly 200 and guide rod assembly 300 of this device adopt a nested design, with a hollow structure, making full use of space. While achieving multi-stage telescopic function, it effectively reduces the overall size, achieving lightweight design, and is more suitable for use in applications with limited space or high weight requirements. This disclosure solves the problem of high manufacturing cost. Compared with the high precision requirements and complex manufacturing processes of the lead screw and related parts in the screw drive scheme, the structure of this device is relatively simple, with fewer parts, reducing the requirements for machining precision and lowering manufacturing costs. Meanwhile, this device avoids the use of complex core transmission components such as the curved stainless steel belt found in gear and rack systems, reducing the application of high-cost parts and further lowering manufacturing costs. This disclosure solves the problem of insufficient transmission stability. The guide rod assembly 300 constrains the circumferential rotation of the drive shaft, ensuring the accuracy of linear motion and avoiding the drawback of continuous deformation of the synchronous belt in synchronous belt drive systems, which affects transmission stability.

[0067] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0068] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0069] Those skilled in the art should understand that the above embodiments are merely for illustrating the present disclosure and are not intended to limit the scope of the disclosure. Those skilled in the art can make other changes or modifications based on the above disclosure, and these changes or modifications still fall within the scope of the present disclosure.

Claims

1. A linear telescopic drive device, characterized in that, include: Fixed base; A drive shaft assembly includes at least two drive shafts. One end of the first-stage drive shaft is rotatably mounted on the fixed base. The remaining drive shafts are nested inside the previous-stage drive shaft and are provided with helical raceways. The helical raceways are channels that extend helically along the outer surface of the drive shaft. The first-stage to penultimate-stage drive shafts are provided with balls, which cooperate with the helical raceways of the next-stage drive shaft through the balls. The guide rod assembly includes a number of guide rods equal to the number of drive shafts. One end of the first-stage guide rod is fixedly mounted on the fixed base. The remaining guide rods are nested inside the previous-stage guide rod. Adjacent stages of the guide rods can only move relative to each other along their length and are constrained to rotate circumferentially by their cross-sectional shapes. The last-stage guide rod is fixedly mounted on the last-stage drive shaft. A drive mechanism is mounted on the fixed base and is connected to the first-stage drive shaft for transmission. When the drive mechanism drives the first-stage drive shaft to rotate, the balls in the upper-stage drive shaft roll and cooperate with the helical raceway of the lower-stage drive shaft, converting the rotational motion of the upper-stage drive shaft into the linear motion of the lower-stage drive shaft, and finally driving the last-stage drive shaft to move linearly along the length direction.

2. The linear telescopic drive device according to claim 1, characterized in that, The drive shafts from the first stage to the penultimate stage are fixedly equipped with bushings, and the balls are disposed on the inner surface of the bushings.

3. The linear telescopic drive device according to claim 1 or 2, characterized in that, A bushing is fixedly installed at the end of the last stage drive shaft, and the end of the last stage guide rod is fixedly connected to the bushing.

4. The linear telescopic drive device according to claim 1, characterized in that, The driving mechanism is a hollow motor, and a channel is provided inside the hollow motor, with the first-stage guide rod fixedly installed in the channel.

5. The linear telescopic drive device according to claim 4, characterized in that, The guide rod is provided with a through hole extending along its length, and the rods are nested sequentially through the through hole; the last bushing is provided with a clearance hole that is opposite to and connected to the through hole; the linear telescopic drive device also includes a drag chain, which is disposed in the through hole of the guide rod, with one end extending from the clearance hole to the outside and the other end extending from the channel of the hollow motor to the outside.

6. The linear telescopic drive device according to claim 1, characterized in that, Limiting devices are provided between two adjacent drive shafts and between two adjacent guide rods. The limiting devices are used to limit the relative range of movement of two adjacent drive shafts or two adjacent guide rods in the length direction so as to keep them in a nested state.

7. The linear telescopic drive device according to claim 1, characterized in that, An elastic element is provided between the ball and the bushing on which the ball is mounted. The elastic element is supported by the bushing and pushes the ball to contact the inner wall of the corresponding spiral raceway.

8. The linear telescopic drive device according to claim 1, characterized in that, The balls are grouped and arranged on the same bushing, and each group of balls includes at least two balls spaced apart; the spiral raceways are grouped and arranged on the same drive shaft, and each group of spiral raceways includes at least two spiral raceways spaced apart, with each spiral raceway and ball being arranged one-to-one.

9. The linear telescopic drive device according to claim 1, characterized in that, When the upper-level drive shaft drives the corresponding bushing to rotate, and the lower-level drive shaft has rotational freedom in the same direction of rotation as the upper-level bushing, the upper-level bushing engages with the helical raceway of the lower-level drive shaft through ball bearings to drive the lower-level bushing to rotate; when the bushing of the upper-level drive shaft rotates, and the bushing of the lower-level drive shaft cannot rotate in the same direction as the upper-level bushing under the constraint of the guide rod or the bushing of the next lower level, the lower-level drive shaft and its bushing move linearly along its length.

10. The linear telescopic drive device according to claim 1, characterized in that, The guide rod is a polygonal tube with a polygonal cross-section.

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